Multi-stage hydraulic hoist



Oct. 18, 1966 J. NOTENBOOM ET AL 3,279,755

MULTI-STAGE HYDRAULIC HOIST Filed Jan. 11, 1965 2 Sheets-Sheet 1INVENTORS ATTORNEYS United States Patent 3,279,755 MULTI-STAGE HYDRAULICHOIST Leo J. Notenboom, Harold M. Peterson, and Joseph J.

Pfeilfer, Kirkland, Wash., assignors to ReDeMan Corporation, acorporation of Washington Filed Jan. 11, 1965, Ser. No. 424,687 8Claims. (Cl. 254-93) This invention relates to a hydraulic hoistmechanism, multi-stage by preference, engineered in particular for usein raising and lowering a work platform such, for example, as ascaffold. The hoist has a piston which works within a cylinder and iscarried upon the lower end of a stanchion smaller in diameter than thecylinder, and there is secured in the outer end of the cylinder both asa stop for the piston and as a guide for the stanchion a header which isgiven a close spline fit with the stanchion.

The hoist employs multiple piston-cylinder assemblies to produce atelescoping standard and it is one object of the invention to devise asystem in which hydraulic fluid supplied under pressure acts first uponthe outermost piston-cylinder assembly to extend the same to its maximumheight and then extends each succeeding pistoncylinder assembly in turn,with the speed of rise being approximately uniform in each instance.

Another Object of the invention is to provide hoist mechanism of thedescribed nature which conveniently adapts itself to various types ofmounting supports as, for example, an automotive truck or wheeledstruts.

As a further object the invention aims to provide a telescopinghydraulic hoist in which each of the hoist cylinders and their pistonsare positively held against rotation.

The invention has the additional object of providing a telescopinghydraulic hoist which is substantially proof against leakage.

The above and yet further objects and advantages in view, looking to theprovision of a hoist requiring little servicing attention and which isof strong, durable and relatively inexpensive construction, will appearand be understood in the course of the following description and claims.The invention consists in the novel construction and in the adaptationand combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIGURE 1 is a fragmentary view partly in vertical section and partly inelevation illustrating a telescoping hydraulic hoist constructed toembody preferred teachings of the present invention.

FIG. 2 is a fragmentary horizontal sectional view thereof on line 22 ofFIG. 1.

FIG. 3 is a fragmentary horizontal sectional view drawn to an enlargedscale on line 3-3 of FIG. 2.

FIG. 4 is a fragmentary enlarged scale vertical sectional view on line44 of FIG. 3.

FIG. 5 is a fragmentary enlarged scale horizontal sectional view on line55 of FIG. 1; and

FIG. 6 is a perspective view indicating the hoist in association with aportable mounting comprised of wheeled struts.

In said drawings we have shown the hoist as being three-stage, andreferring to such drawings the numerals 10, 11 and 12 denoteinterfitting cylinder members for the first, the second, and the thirdstages, respectively. Each said cylinder member is open at the top withinternal threads surrounding its top opening, and at the bottom providesan end wall, as 13, 14 and 15. Each of these end walls has athrough-bore, as 16, 17 and 18, in its center, sized so that, for eachof the three cylinders, much the same ratio exists as between its arealcompass and 3,279,755 Patented Oct. 18, 1966 the flow capacity of thebore which is provided in its end wall. The bore 16 is tapped to receivesuitable fittings 20 accommodating a flexible hose which connects thehoist with a 3-position control valve (not shown), such valve eithersupplying from a pump a governed volume of pressure fluid to the hoist,locking the fluid in the hoist, or dumping such fluid to a reservoirfrom which the pump draws its supply.

The outer cylinder member 10 serves as a base for the hoist, and isprovided exteriorly with two set of vertically spaced circumferentialgrooves adapted to receive snap-rings 21. The two sets of snap-rings arelocated one adjacent the top and one adjacent the bottom of the cylindermember, and each is adapted to hold a respective one of two collars, as22 and 23, in place upon the cylinder member. The collars present ashoul der at one end and at the other end are threaded. A pair ofmounting rings, as 24-25 and 26-27, are journaled for turning motionupon the collars, occupying positions one above the other between theshoulder and a locktype keeper ring 28 which threads on the collar. Ascan be understood from an inspection of FIG. 6, eyed lugs extendradially outwardly from each mounting ring at diametrically oppositesides thereof, and legs for the standard are attached to these lugs. Thelegs and the manner of their attachment to the standard are the subjectmatter of a separate application now in process of preparation butsuflice it to here say that each leg carries a ground wheel 30 togetherwith a ground-engaging screw jack 31 at its outer end, comprises innerand outer sections articulating for relative swing motion about avertical axis, and has upper and lower arms which diverge toward thecollars.

Proceeding now to describe the extension mechanism of my multi-stagehoist, the first-stage cylinder member 10 has an inside diametersubstantially larger than the outside diameter of the second-stagecylinder member 11. The second-stage cylinder member likewise has aninside diameter substantially larger than the outside diameter of thethird-stage cylinder member 12. Such third-stage cylinder member, inturn, has an inside diameter substantially larger than the outsidediameter of a cylindrical stanchion 33 which is received therein. Thespaces 34, 35 and 36 which are thereby provided are occupied by threepistons 37, 38 and 39. Each piston is ring-shaped and is carried at thelower end of the cylinder member 11, the cylinder member 12, or thestanchion 33, as the case may be. The pistons each fit a necked-downportion (see FIG. 4) which is provided at the lower end of the relatedmember. The pistons are held in place by snap-rings 40 seating incircumferential grooves. Each piston has a static seal 41 at the inside,and at the outside is fitted with a compression seal 42 and a wear strip43. The static seal is or may comprise a neoprene O-ring. A nylon beltis suitable as a wear strip, and for the compression seal we prefer toemploy an O-ring of neoprene occupying a downwardly facing skirtedpocket formed in a band of self-lubricating plastic such, for example,as graphited polyurethane. By reason of the differences in diameter thelift capacity of the surface 14-37 is greater than that of the surface15-38, and the latter is in turn greater than that of the horizontalsurface exposed by the stanchion including its piston 39.

Extending between the necked-down portions and the upper extreme end ofeach of said members 11, 12 and 33 there is provided a longitudinalgroove, as 44, 45, and 46. These grooves each accommodates a key, as 47,48 and 49, extending inwardly from a respective one of three glands 50,51 and 52, or headers as they will be hereinafter termed. The headersare externally threaded to engage said internal threads which lie at theupper end of the three cylinder members 10, 11 and 12, being lockedagainst turning by Allen-headed screws 53. Header 50 closely fits thecylinder member 11. Header 51 closely fits the cylinder member 12.Header 52 closely fits the stanchion. A respective ring 57 of filtermaterial, felt for example, is carried by each header in a suitablegroove extending circumferentially about the inner perimeter, and servesto pass air into and from the spaces 34, 35 and 36 as the pistons movetherein. A respective snap-ring, as 54, 55 and 56, received in acircumferential groove located a moderate distance above each pistonacts by its engagement with the related header to prescribe for thepistons a maximum length of travel such that each of the three members11, 12 and 33, when fully extended, retains a stable bearing againstlateral deflection. Should any air be present in the hydraulic systemthe same is bled by a valve 58 from the head end of an open-bottomcenter bore 59 formed in the stanchion.

When applied to the use for which the same has been primarily designed,namely the support of an elevatortype scaffold, two hoists each mountedso as to be substantially vertical are used with one end of the scaffoldbearing upon the head end of one stanchion and the other end bearingupon the head end of the other stanchion. The collar 22 has radial armswhich carry levelling bubbles. Should it be desired, the hoists andscaffold can be mounted upon a truck. It is preferable in such anapplication that the lower end of the hoist have a gimbal mounting andfor this purpose we prolong the outer cylinder member below its bottomwall and provide bearings 60 for trunnion pins (not shown). The lowerset of mounting rings 26-27 are dispensed with, and a respective one oftwo strutseach adjustable as to length by a turn-buckle-is attached toeach of the two mounting rings 24-25. The two struts extend diagonallyfrom the hoist to a suitable anchor fitting provided on the truck, oneoccupying a longitudinal vertical plane and the other a transversevertical plane.

As will, it is thought, be apparent hydraulic fluid delivered underpressure to the hoist first exerts thrust upon the bottom wall of thecylinder member 11. Such member, together with the cylinder member 12and the stanchion 33, rise bodily until the snap-ring 54 is broughtagainst the head-ring 50. The cylinder member 12 continues to rise untilits travel is interrupted by the engagement of snap-ring 55 with thehead-ring 51. Stanchion 33 then provides the third-stage rise of thehoist. It will be noted that annular ribs protrude below the bottom'wall of the two cylinder members 11 and 12 so that each of said bottomwalls exposes a large area to the -lift pressure of the incominghydraulic fluid.

It is believed that the invention will have been clearly understood fromthe foregoing detailed description of our now-preferred illustratedembodiment. Changes in the details of construction may be resorted towithout departing from the spirit of the invention and it is accord-.ingly our intention that no limitations be implied and that the heretoannexed claims be given the broadest interpretation to which theemployed language fairly admits.

What we claim is: 1. A hoist comprising a body member having an open-'top annular cylinder of extended length therein with a closing wall atthe bottom, said bottom wall having an opening for delivering fluidunder'pressure to the cylin der and for dumping said fluid therefrom, apiston of comparatively short length fitting said cylinder, a stanchionof circular cross-section having a diameter substantially less than thatof the cylinder and a length at least as long as the cylinder receivedwithin the cylinder, means attaching said piston to the lower end of thestanchion, a header having a spline fit upon the stanchion and occupyingthe space between the stanchion and the body member at the top end ofthe cylinder, and means detachably securing said header to the bodymember holding the header against displacement in a direction endwise tothe cylinder, the lower end of the stanchion being necked down toprovide a seat for the piston, the interior and exterior surfaces of thepiston being circumferentially grooved, sealing rings being received inboth of said grooves.

2. In a multi-stage hydraulic hoist: a series of interfitting memberscomprising a stanchion of circular crosssection at the inside, acylinder member at the outside, and at least one median cylinder membertherebetween, the cylinders of said median and outer cylinder membersbeing open at the outer end, closed at the inner end, and havingadiameter which is in each instance substantially larger than theoutside diameter of the next smaller member of the series, the wallswhich close said inner ends having through-openings therein for deliveryof pressure hydraulic fluid to and dumping of hydraulic fluid from thecylinders, said inner cylinder member and the stanchion each having anannular piston carried upon the lower end thereof closely fitting thewall of the surrounding cylinder, sealing rings for the pistons, and arespective header carried by each cylinder member at the outer endthereof having a close spline fit with the next smaller member of theseries.

3. A hydraulic hoist according to claim 2 in which the through-openingin the wall which closes the inner end of the outer cylinder member isappreciably larger than that which closes the inner end of the mediancylinder member.

4. A hydraulic hoist according to claim 2 in which the stanchion has acenter-bore extending the substantial length thereof with the lower endopen for access of hydraulic fluid from the cylinders of the hoist andwith the upper end closed by an air-bleeding valve.

5. A hydraulic hoist according to claim 2 in which the spline fitprovided for each header comprises a key carried by the concerned headerreceived for sliding movement in a key-way formed in the member which itfits, each header being formed interiorly with a circumferential groove,and having a ring of filter material seated therein.

6. A hoist as claimed in claim 2 in which both the inside and theoutside surface of each piston is circumferentially grooved and having arespective one of said sealing rings received in each groove the innerring to produce a static seal and the outer ring to produce acompression seal, said outer surfaces being each provided with anadditional circumferential groove to receive a wear strip.

7. A hoist as claimed in claim 2, and upper and lower mounting collarssleeved upon the outer cylinder each having a respective pair ofmounting rings journaled for rotation thereon.

8. A hoist comprising a body member having an opentop annular cylinderof extended length therein with a closing wall at the bottom, saidbottom wall having an opening for delivering fluid under pressure to thecylinder and for dumping said fluid therefrom, a piston of comparativelyshort length fitting said cylinder, a stanchion of circularcross-section having a diameter substantially less than that of thecylinder and a length at least as long as the cylinder received withinthe cylinder, means attaching said piston to the lower end of thestanchion, a header having a spline fit upon the stanchion and occupyingthe space between the stanchion and the body member at the top end ofthe cylinder, means detachably securing said header to the body memberholding the header against displacement in a direction endwise to thecylinder, said spline fit between the stanchion and the headercomprising a key provided by the header and received in a key-wayprovided by the stanchion, the header being formed interiorly with acircumferential groove, and a ring of filter material seated in saidinterior groove and having a profile configuration, interior surfaceconsidered,

5 6 corresponding to the exterior profile of a cross-section of2,143,182 1/ 1939 Barr. the stanchion including the key-way. 2,854,95810/195 8- Wood et a1 9253 References Cited by the Examiner 6/1964 Walker91 168 UNITED STATES PATENTS 5 WILLIAM FELDMAN, Primary Examiner.1,069,863 8/1913 DBSPiIIS 91 -169 X OTHELL SIMPSON E j 2,002,428 5/1935Black.

1. A HOIST COMPRISING A BODY MEMBER HAVING AN OPENTOP ANNULAR CYLINDEROF EXTENDED LENGTH THEREIN WITH A CLOSING WALL AT THE BOTTOM, SAIDBOTTOM THEREIN WITH A OPENING FOR DELIVERING FLUID UNDER PRESSURE TO THECYLINDER AND FOR DUMPING SAID FLUID THEREFROM, A PISTON OF COMPARATIVELYSHORT LENGTH FITTING SAID CYLINDER, A STANCHION OF CIRCULARCROSS-SECTION HAVING A DIAMETER SUBSTANTIALLY LESS THAN THAT OF THECYLINDER AND A LENGTH AT LEAST AS LONG AS THE CYLINDER RECEIVED WITHINTHE CYLINDER, MEANS ATTACHING SAID PISTON TO THE LOWER THE STANCHION ANDOCCUPYING THE SPACE BETWEEN THE STANCHION AND THE BODY MEMBER AT THE TOPOF END SPACE CYLINDER, AND MEANS DETACHABLY SECURING SAID HEADER TO THEBODY MEMBER HOLDING THE HEADER AGAINST DISPLACEMENT IN A DIRECTIONENDWISE TO THE CYLINDER, THE LOWER END OF THE STANCHION BEING NECKEDDOWN TO PROVIDE A SEAT FOR THE PISTON, THE